[1] Although studies of fish oil supplements, which contain both docosahexaenoic acid (DHA) and EPA, have failed to support claims of preventing heart attacks or strokes,[2][3][4] a recent multi-year study of Vascepa (ethyl eicosapentaenoate, the ethyl ester of the free fatty acid), a prescription drug containing only EPA, was shown to reduce heart attack, stroke, and cardiovascular death by 25% relative to a placebo in those with statin-resistant hypertriglyceridemia.

Medical conditions like diabetes or certain allergies may significantly limit the human body's capacity for metabolization of EPA from ALA.

Commercially available dietary supplements are most often derived from fish oil and are typically delivered in the triglyceride, ethyl ester, or phospholipid form of EPA.

[16] Similarly, DHA or EPA in the lysophosphatidylcholine (LPC) form was found to be more efficient than triglyceride and phosphatidylcholines (PC) in a 2020 study.

[17] Aerobic eukaryotes, specifically microalgae, mosses, fungi, and most animals (including humans), perform biosynthesis of EPA usually as a series of desaturation and elongation reactions, catalyzed by the sequential action of desaturase and elongase enzymes.

[19] The proposed polyketide synthesis pathway of EPA in Shewanella (a marine bacterium) is a repetitive reaction of reduction, dehydration, and condensation that uses acetyl-CoA and malonyl-CoA as building blocks.

The resulting structure is converted by NADPH dependent reductase, KR, to form an intermediate that is dehydrated by the DH enzyme.

[20] The US National Institute of Health's MedlinePlus lists medical conditions for which EPA (alone or in concert with other ω-3 sources) is known or thought to be an effective treatment.

Dietary supplements containing EPA and DHA lower triglycerides in a dose dependent manner; however, DHA appears to raise low-density lipoprotein (the variant which drives atherosclerosis, sometimes inaccurately called "bad cholesterol") and LDL-C values (a measurement/estimate of the cholesterol mass within LDL-particles), while EPA does not.

A Cooper Center Longitudinal Study that followed 9253 healthy men and women over 10 years revealed that those who took fish oil supplements did not see raised LDL-C levels.